The Community Builder (CB) suite extends the Joomla! user management system, and allows you to use Joomla! to build a customizable social networking Web site. Its key features are extra fields in a profile, enhanced registration workflows, user lists, connection paths between users (friends), administrator-defined tabs and user profiles, image upload, front-end workflow management, and integration with other components, like PMS, Newsletter, Forum, and Galleries. Many plugins are available for adding more features. CB is compatible with all versions of Joomla! 1.5 native, Joomla! 1.0.x native, and Mambo 4.5.2-4.6.5. CB allows multi-criteria user searches, full field controls of core fields, AJAX email and username checkers, image and integer fields, custom validations, and many more features.

ConcourseConnect is a social networking platform. You can build social networking sites including corporate intranets, business community add-on sites, enthusiast sites, business or product directory sites (like a chamber of commerce or yellow pages), or even stand-alone Web sites. Features include a full range of Web 2.0 tools: ratings, reviews, wiki, blog, comments, discussion forums, an ideas engine, and more. Users begin by creating a rich profile and joining groups. It is perfect for internal collaboration or as a customer feedback forum. The portal framework allows developers to plug in custom portlets and themes.

Crabgrass is social networking, group collaboration, and network organizing Web application. It consists of a solid suite of group collaboration tools such as private wikis, task lists, a file repository, and decision making tools. Work is currently being done on a large user interface overhaul, better social networking tools, blogs, and event calendars, as well as better support for collaboration and decision making among independent groups.

Cysphere is an integrated social networking server for smaller virtual communities. It provides a private mailbox, public and private discussion forums, and simple file sharing, and makes it as simple as possible for users to communicate over the Web in a secure way. It includes an embedded Web server and SQL database and requires no installation or maintenance.

Elgg is a professional social networking platform that empowers individuals, groups, and institutions to create their own fully-featured social network. It can also be used as a basis for developing custom networks using powerful hooks and APIs.

For Human Eyes Only is a Firefox plugin that lets you post in a way that prevents computers from analyzing your messages. The plugin converts your messages into images in a way that makes it hard for computers to extract your message, while genuine humans can still read it.

Mahara is a fully featured electronic portfolio, blog, resume builder, and social networking system for connecting users and creating online communities. It integrates with Moodle and many online services.

NetworX Non-Profits is scalable software that allows non-profit organizations to create their own branded Web site for building an online community with the the organization's donors, volunteers, and foundations. This Web site includes features for collecting donations, sending messages to registered email addresses, managing membership and volunteers, managing programs and resources, displaying a calendar of upcoming events, collecting registrations for events, letting visitors search for events, and analyzing statistics about donations, programs, and visitors.

Open-Xchange Server Edition is a multi-tier, small footprint solution that integrates seamlessly into customer’s architectures, enabling smooth start of operation based on services. The Open-Xchange Server Edition supports different Enterprise Linux systems like SUSE Linux Enterprise Server 10, Red Hat Enterprise Linux 5, and Debian Etch. Users are presented with a highly advanced, improved, and intuitive browser based interface that meets all their email, calendaring, tasking, contacts, and document storage requirements. Further integrations like LDAP-support or ADS are possible. It's designed for medium organizations and educational and public administrations that want to have a customizable communication solution.

PHP On Pie is a PHP framework that combines the best ideas from PHP projects like Drupal, CodeIgniter, Kohana, and ZendFramework. It has very few core concepts: classes, models, events, slots, and tools. It lets you repackage completed apps into plugins that you or others can use later. Its smart database classes allow you to implement vertical and horizontal partitioning (sharding) easily to handle millions of users.